LISA vs Endotracheal Surfactant in Preterm Neonates: A Lung Ultrasound Distribution Study

Surfactant Distribution Homogeneity Index (SDHI) Derived from Lung Ultrasound Imaging scores pre and at 60 Minutes Post-Surfactant Administration.

A novel metric calculated from the change in regional Lung Ultrasound (LUS) scores before and after surfactant administration. The(SDHI) quantifies the uniformity of surfactant distribution across lung regions. The SDHI will be calculated 1 hour after surfactant administration. A higher SDHI is hypothesised to indicate more homogeneous distribution of surfactant across the lungs. Each infant will have a single SDHI value post-intervention, and this will be compared between the LISA and ETT groups to evaluate whether one administration method achieves superior surfactant distribution homogeneity. The SDHI evaluates the homogeneity of surfactant distribution using multiple formulations applied to regional LUS score changes across 12 predefined lung regions (anterior, lateral, and posterior zones for both left and right hemithoraces). The computation involves comparing regional LUS improvements SDHI (dimensionless index); higher values indicate more homogeneous surfactant distribution

Change in Total Lung Ultrasound Score (LUS) from Baseline to 60 Minutes Post-Surfactant Administration

The Lung Ultrasound Scoring System (LUSS) will be used to quantify lung aeration. Each of 12 predefined lung regions (anterior, lateral, and posterior zones for both left and right hemithoraces) will be scored on a scale from 0 to 3, where: 0 = normal aeration (no B-lines), 1 = moderate aeration (B-lines \<50% of region), 2 = poor aeration (B-lines ≥50% of region), and 3 = consolidation. Higher scores indicate worse aeration. Total LUS score ranges from 0 (best) to 36 (worst). Regional changes will be analyzed by anatomical zone (anterior-posterior, left-right) to assess distribution homogeneity. The primary analysis will report the mean change in total LUS score and regional LUS scores for each study arm, with comparison between LISA and ETT groups. Scale Name (Unabbreviated): Lung Ultrasound Scoring System (LUSS) Minimum Value: 0 Maximum Value: 36 Higher Scores Indicate: Worse aeration (lower is better outcome)

Number of Participants Requiring Invasive Mechanical Ventilation Following Initial Surfactant Administration

The proportion of infants in each arm (LISA vs. ETT) who require intubation and invasive mechanical ventilation after the initial surfactant dose. This is a binary outcome (yes/no) and will be reported as the number and percentage of participants in each arm requiring mechanical ventilation. Mechanical ventilation is defined as the need for endotracheal intubation with positive pressure ventilation support. The analysis will compare the rate of mechanical ventilation requirement between the two study groups to evaluate whether LISA reduces the need for invasive ventilation compared to standard ETT administration. Measurement Unit Count and percentage of participants (0-22 participants per arm)

Number of Participants Requiring a Second Dose of Surfactant Due to Persistent Respiratory Distress Syndrome

The proportion of infants in each arm (LISA vs. ETT) who require a second dose of exogenous surfactant due to persistent or worsening radiographic and clinical evidence of Respiratory Distress Syndrome (RDS). This is a binary outcome (yes/no) and will be reported as the number and percentage of participants in each arm requiring repeat surfactant dosing. Repeat dosing is determined by the clinical team based on persistent RDS criteria, including radiographic findings and clinical respiratory severity. The analysis will compare the rate of repeat surfactant requirement between the two study groups to evaluate the efficacy of each administration method in providing adequate initial surfactant distribution. Measurement Unit Count and percentage of participants (0-22 participants per arm)